There are several triangle origami designs in my new book that are able to hold various things. From simple to complex, these origami designs provide organization and protection.
Envelopes
Design number 33, Self Sealed Envelope, is presented on page 112 and 113. This is a flat cylinder that takes one end and nests a folded section of the tube back into itself. Relatively fast to make, two of these can be made in slightly different widths, a narrower one's open end being covered by the open end of a wider one. Fully contained something. Stopping at just one of these with the open end cuffed in for stability, an effective pen case is found.
Boxes
These open more options for larger or bulkier items.
One relatively fast option is design number 45, Fast Maximal Open Cube, page 52 and 53. This open cube is similar to the Ho Tsak-man, Haruo Hosoya cube modules diagrammed and discussed on page 48 and 49. Like that earlier design, and like other boxes, one example of the Fast Maximal Open Cube may be covered and closed by another.
Antiprisms
For this, my favorite and primary example is the one which I first diagrammed, design 00, Open Triangular Antiprism
from Equilateral Triangle, appearing in my Triangle Origami Book on page 20 and 22, and my diagram for the nested arrangement of these, design 02, Octahedron Box
from Open Triangular Antiprism, illustrated one discussed on page 24 and 25. While describing this fully would be redundant in light of the book, I will simply state my finding that the twist required for nesting antiprisms makes them useful as stable secure packages.
If you enjoyed this, or find any of this useful, please consider sharing this with others and perhaps purchasing my book. For information please check out triorigami.com